The objective of the proposed research is to discover the normal and pathological mechanisms by which the collagen and the protein- polysaccharide complexes of human cartilage matrix are broken down. This will involve the characterization and quantitation of at least 5 proteolytic enzymes in normal cartilage and in cartilage from osteoarthritis and rheumatoid arthritis patients. We have recently shown that cartilage cathepsin D is totally incapable of digesting the protein-polysaccharide complexes of the cartilage matrix at neutral pH. However, cartilage, including human cartilage, contains one or more neutral proteases capable of degrading these complexes. The major part of this project is devoted to characterizing the neutral protease that can digest the matrix, and quantitating it in various disease states. Collagenase, acid collagenolytic cathepsin, and PZ-peptidase will also be explored. An important aspect of these enzyme studies will be the development of micromethods for assay of enzymes in minute amounts of tissue taken from different regions of the same cartilage surfaces; this will permit sampling of different small zones in and about lesions and at different depths from the surface. The proposed research would be of importance in understanding the disease processes involved in arthritis as well as the normal processes of cartilage remodeling and calcification.